1. Field of the Invention
The present invention relates generally to a connection device disposed on a mobile phone, PHS (Personal Handyphone System) and other mobile information terminals for connection with external devices such as peripherals, and, more particularly, to antistatic measures for a connection device and electronic equipment having the connection device.
2. Description of the Related Art
Mobile phones are provided with connection devices such as charge terminals and USB (Universal Serial Bus) connection terminals. With such connection devices, charge terminals are connected to a charger for charging the built-in secondary battery, whereas USB connection terminals and others are connected to external equipment such as personal computer for exchanging information. Connection terminals provided on a mobile phone are exposed outside the case to facilitate connection with the charger or external equipment and are therefore subjected to an electrostatically charged environment such as human body.
Japanese Utility Model Registration No. 3078521 and Japanese Patent Application Laid-Open Publication No. 2000-347790 are among prior patent documents in relation to these connection devices and antistatic measures thereof.
Japanese Utility Model Registration No. 3078521 discloses, as a USB connector with upgraded grounding effect, one in which the connector's grounding effect has been upgraded by establishing electrical continuity between the metal case and the electrical conduction means through connection. Meanwhile, Japanese Patent Application Laid-Open Publication No. 2000-347790 relates to a keyboard apparatus and discloses, as a USB-compatible keyboard apparatus preventing defects caused by electrostatic noise such as malfunction and faulty operation, a construction in which a shield plate is provided covering the underside of the control circuit board and the shield plate is electrically connected to the USB connector's frame ground portion and to the shield wire of a cable connected to the personal computer (“PC”) main body.
Incidentally, electrostatic discharge—resulting from static electricity from a human body, etc., acting on the USB and other connection terminals exposed on a mobile phone-leads to a high voltage being applied to the circuit board side of the mobile phone, possibly damaging the circuitry in the circuit board side or resulting in malfunction.
While the aforementioned patent documents present the problem in respect of electrostatic countermeasures, they are not designed to ensure electrostatic damage prevention or lightning protection for connection devices used for external connection.